Process for cleaning of oil-laden metal waste to recover the metal and to reclaim the oil

ABSTRACT

(C) MIXING THE SLUG WITH THE WASHED METAL WASTE; AND (D) DRYING THE MIXTURE OF SLUG AND METAL WASTE.   1. A CONTINUOUS NON-BATCH PROCESS FOR CLEANING OILLADEN METAL WASTE TO RECOVER THE METAL AND TO RECLAIM THE OIL CARRIED BY THE METAL WASTE, COMPRISING THE STEPS OF: (A) WASHING THE METAL WASTE WITH DETERGENT, AND EFFECTING RELATIVE MOVEMENT BETWEEN THE WASTE AND THE DETERGENT TO CREATE A COUNTER-CURRENT THEREBETWEEN; (B) SEPARATING OIL AND DETERGENT FROM THE WASH RESIDUE TO LEAVE A SLUDGE CONTAINING MOISTURE AND DIRT PARTICLES;

IHRIG PROCESS FOR CLEANING OF OIL -LADEN METAL WASTE TO Nov. 5, 1974RECOVER THE METAL AND'TO RECLAIM THE OIL 3 Sheets-$heet 1 Filed March16, 1973 Nov. 5, 1974 .1. K. IHRIG 3,846,173

PROCESS FOR CLEANING OF OIL-LADEN METAL WASTE TO RECOVER THE METAL ANDTO RECLAIM THE OIL Filed March 16, 1975 3 Sheets-Sheet 2 B6 n W I G a as52 4o i: ll l 48 Nov. 5, 1974 J, |HR|G 3,845,173

PROCESS FOR CLEANING OF OIL-LADEN METAL WASTE T0 RECOVER THE METAL ANDTO RECLAIM THE OIL Filed March 16, 1973 3 Sheets-Sheet 3 United StatesPatent O 3,846,173 PROCESS FOR CLEANING F OIL-LADEN METAL WASTE TORECOVER THE METAL AND TO RE- CLAIM THE OIL John Kenneth Ihrig, Glenwood,111., assignor to FMC Corporation, San Jose, Calif. Filed Mar. 16, 1973,Ser. No. 342,014

Int. Cl. B08b 3/08, 3/10; C23g 1/36 U.S. Cl. 134-10 22 Claims ABSTRACTOF THE DISCLOSURE A continuous process for cleaning metal waste, such asturnings, borings and chips. A detergent is contacted with the metalwaste in a counter-current flow to remove 011 and other impurities andthe wet sludge, removed during the clarification of the detergentsolution in a rehabilitation circuit, is mixed with the cleaned metalwaste and both are simultaneously dried. Makeup water is added to thecleaned metal waste ahead of the dryer to further rinse a substantialportion of any remaining detergent solution from the metal waste andthis rinse liquid with the recovered detergent solution is returned tothe rehabilitation circuit to reduce the amount of concentrated makeupdetergent solution required.

BACKGROUND OF THE INVENTION Field of the Invention Large quantities ofmetal waste such as metal chips, turnings, borings, etc., are produceddaily by manufacturing industries. The recovery of the metalliccomponent and the reclaiming of the lubricating and/or cutting oilscoating these metal particles are of commercial importance. Toaccomplish these ends it is necessary to remove impurities such as dirtfrom the mixture and to have a high percentage of oil and moistureremoved from the metal component, usually to a level of less than 2percent by weight on the recovered metal product, so the metal productis suitable for briquetting or for feeding directly to a meltingfurnace.

This invention relates to the art of cleaning metal waste, such as metalchips, turnings, borings, and the like, and reclaiming oil from suchwaste.

'Description of the Prior Art In the previously granted patents, U.S.3,544,369 and U.S. 3,639,172 to James R. Keogh, In, and assigned to thesame assignee as the present application, there are contained specificprocess steps for the cleaning of metal waste by washing in a detergentsolution and the rehabilitation of the dirty washing solution so it canbe recycled. In the rehabilitation of the detergent solution, wet sludgeis removed from the detergent solution, but no means is disclosed forthe continuous disposal of this separated sludge.

'In S. A. Goodstein, U.S. Pat. 3,163,929, dirty chips are washed in adetergent solution in a rotary drum and then further sprayed withdetergent laden steam to dry the chips without any rehabilitation of thedirty detergent solution. In G. T. Hittel et al., U.S. Pat. 3,454,428,and in T. J. Kearney, U.S. Pat. 3,610,260, a chlorinated type of solventis used to remove the oil. In G. T. Hittel et al. the solvent is furtherremoved from the chips and recovered by use of centrifugal force. A moregeneral type of process of cleaning oily chips by the extraction of theoil by centrifugal force is exempli fied by the following patents: U.S.2,906,466 to A. O. Hoper; U.S. 3,656,620 to C. R. Larson et al. and U.S.3,679,051 also to C. R. Larson et a1. Another general type of process ofcleaning metal chips includes the burnice ing off of the oil and theevaporation of the moisture. This process is exemplified by thefollowing patents: U.S. 2,852,418 and U.S. 2,925,821 both to W. D.MacDonald; U.S. 3,544,367 to F. Ehrlich et al.; U.S. 3,598,649 to A. M.Juhasz; U.S. 3,601,900 to M. J. Erisrnan et al.; U.S. 3,619,908 to W. C.Kallas and U.S. 3,656,735 to S. A. Eliot. A. H. Brisse, U.S. Pat.2,529,762, discloses means for cleaning continuous metal strip in acleaning solution and then drying the strip with the use of steam.

SUMMARY OF THE INVENTION In one step of the present invention, sludgeremoved from the metal during cleaning is mixed with the washed metalfor drying. In another step of the method of the present invention,makeup water is added to the clean metal waste to rinse detergentremaining thereon into a settling tank for reuse.

In the preferred form of the invention, the process utilizes a heateddetergent solution in a wash bath in which the metal waste is agitatedto thoroughly expose all of the surfaces of the metal waste to thecleaning action of the detergent solution as it passes through the bath.The discharged clean metal is then further dried to reduce its moisturecontent. The dirty oil laden detergent solution is removed and passedthrough a rehabilitation circuit to clarify it by removing the oil andsludge contained thereon. Upon adding of makeup detergent and reheatingof the restored solution, the added and restored solution isrecirculated to the wash bath.

'In the clarification of the detergent solution, wet, sticky sludge(consisting of, for example, 35% moisture and fine particles, primarilydirt) is removed which is difficult to handle. Since a 20 ton per hourfeed rate of metal waste on a continuous cleaning system might produceas much as 5 tons of sludge in 8 hours of operation, the problem ofhandling this sludge is of distinct importance. In the presentinvention, after the oil has been removed therefrom, this sludge iscontinually mixed with the feed of the cleaned metal waste going to thedryer. The wet sludge is then dried with the metal waste, and the finelight impurities pass out into the dust collector with the heated air.The heavier solids, usually metal, are discharged from the dryer withthe dried metal waste.

In addition, in the preferred form of the invention further detergentsolution can be recovered for recycling by adding the makeup water tothe cleaned metal waste as it is conveyed to the dryer, thus rinsingthis metal Waste of a substantial portion of any detergent solutionremaining on the metal waste after it leaves the wash bath. This rinsewater is then conducted to the settling basin in the rehabilitationcircuit where it is added to the restored detergent solution, thusreducing the amount of required makeup detergent solution. Since it isestimated that makeup detergent is nearly 50 percent of the total hourlyoperating cost, the recovery and reuse of this detergent solution fromthe new rinsing operation will substantially reduce the hourly operatingcost of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the apparatusused in the metal waste cleaning process of the present invention.

FIG. 2 is an elevational view of the apparatus used in the metal wastecleaning process of the present invention.

FIG. 3 is a cross-sectional view taken along lines 33 of FIG. 1.

FIG. 4 is a cross-sectional view taken along lines 4-4 of FIG. 1.

FIG. 5 is a diagrammatic view with certain components in section,showing the overall interrelationship between components of a metalwaste cleaning system in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present process of cleaningoil-laden metal waste provides improvements over the aforementioned U.S.Pats. 3,554,369 and 3,639,172, but utilizes the same types of detergentsolutions described therein. One such solution employing Oakite No. 24,as made by Oakite Products, Inc., New York, N.Y., U.S.A., is an alkalinedetergent containing soap, silicates and caustic. When used at aconcentration of approximately this detergent has been found to providedesirable results with some metals, particularly cast iron and steel.Oakite cryscote No. 187, also made by Oakite Products, Inc., New York,N.Y., U.S.A., is an acidic detergent containing phosphates, activatingagents and solvents, and, when used at a concentration of approximately3%, has been found to provide desirable results with other metals,particularly brass. Although the type of detergent employed may varydepending on the types of metal and oil encountered, solutions rangingbetween 2% and by weight are effective in removing a substantialquantity of oil from the metal. In addition, detergent solutions of suchstrength allow the oil to separate from the detergent solution uponstanding in a settling tank or upon the application of centrifugal forceto such solution such as that encountered in a centrifuge. The retentiontime for the metal waste within the wash bath may vary depending uponthe type of detergent employed and its concentration. Preferable resultshave been obtained using the Oakite No. 24 at 180 F. at approximately 5%strength with a retention time of two minutes while feeding metal wasteto the washer at a rate of approximately 1750 pounds per hour and whilerecirculating approximately 8100 pounds per hour of detergent solution.The retention time, however, may vary within the range of one to sixminutes.

In order to maintain the detergent solution at the desired strength andin proper condition for removing a substantial quantity of oil from themetal waste, it is necessary to remove or separate the sludge and oiland to add makeup detergent. It is also particularly desirable to heatthe detergent solution to obtain maximum etficiency in removing the oilfrom the metal waste.

The apparatus used to carry out the present process is shown in FIGS.1-4. FIG. 5 is a schematic flow diagram of the present process using theapparatus shown in FIGS. 1-4 and for which the same part numbers areshown for corresponding apparatus items; A washer, generally shown as10, is fed with ground metal waste from a feed hopper 12 by a conveyor14. The washer 10, has a tank 16 with an inclined bottom 17 forming alower end 18 with an overflow weir 19 and an upper end 20 with adischarge chute 21. A power driven screw 22 is disposed within the tank16 parallel to the inclined bottom 17. As illustrated in FIGS. 1 and 2,the washer 10 may contain two like units in series to provide longerretention time of the metal waste in the washer. Heated detergentsolution is fed into the upper end of each washer from spray pipes 24.The detergent solution forms a wash bath 25 in the lower end 18 of eachsection of the washer. As indicated by arrow 26 (FIG. 5) the detergentsolution flows down toward the lower end 18 while the screw 22 conveysthe metal waste, submerged in the wash bath in the direction of arrow 28upwardly toward the upper end 20 to obtain counterflow of metal wasteand detergent solution. With the two units in series, as shown, the washbath level in the second unit is maintained so that the detergentoverflows into the first unit and when the wash bath level in the first,or lower unit, reaches the level of the overflow weir 19, the dirtydetergent solution is discharged from .the washer through conduit 30.The inclined section of the upper end of the tank and the screw extendsbeyond the level of the wash bath towa d the discharge end to provide adrainage section for removing much of the moisture on the cleaned wastebefore the waste is discharged to chute 21.

The cleaned metal waste is transferred from chute 21 by a conveyor 32 toa drying system generally shown as 35. The dryer system 35 includes arotary cylindrical dryer unit 36 with a drive 37 and a discharge hood38, an air heater furnace 40, a dust collector 42 and an exhaust fan 44.The cleaned metal waste is fed into the dryer unit 36 through a feedinlet chute 46 and proceeds longitudinally through the dryer 36 to thedischarge hood 38. Dryer unit 36 may be of the convention single shelltype which is then positioned to rotate about an axis inclineddownwardly toward the discharge and is driven by drive unit 37. The wetfeed material is then lifted and tumbled, as the shell is rotated,through a hot air stream provided by the air heater furnace and causedto flow counterfiow to the metal waste by the exhaust fan 44 locatedbeyond the dust collector 42. Dust collector 42, which may be of aconventional cyclone type, provides means for the dust and other fineimpurities carried by the air stream to settle out of the air stream toa lower collection hopper 43 in the bottom of the dust collector. Thedried metal waste is discharged from the dryer 36 into the dischargehood 38. Typical means of handling the dryer discharge, as shown in FIG.4, may include a conventional power driven screw feeder 48, feeding theclean dried metal waste into a conventional power driven bucket elevator50 which elevates this material to a convenient height where a secondconventional power driven screw feeder 52 may feed this material to itspoint of ultimate use, such as a briquetting machine.

The dirty oil-laden detergent solution, after passing overflow weir 19,flows through conduit 30 to a detergent solution rehabilitation circuitgenerally indicated as 55 for removal of the sludge and oil picked up bythe detergent solution in the washer 10. In the rehabilitation circuit,which follows the process disclosed in the aforementioned US. Pat.3,639,172, the detergent solution is restored and is then recirculatedthrough a conduit 56 to the spray pipes 24 on the washer 10.

In the rehabilitation circuit 55 (FIG. 5) the dirty detergent solutionfrom the overflow weir 19 of the washer normally passes through conduit30 and open valve 31 to a centrifuge 58 to remove any solids and thesludge present in the dirty detergent solution. The cleaned detergentsolution is then passed through conduit 60 and pump 62, if required, toa settling basin 64. This settling basin is provided with a high leveloverflow weir to permit any excess solution to be accumulated in astorage vessel 66.

Storage vessel 66 also provides means for maintaining the continuousflow of dirty detergent solution from the washer while the sludgeremoval centrifuge 58 is intermittently shut down for cleaning and/orrepairs so the metal Waste washing may proceed continuously. When theflow of dirty detergent solution to the sludge removal centrifuge 58 isthus interrupted, valves 31 and 33 (FIG. 5) are closed and valve 34 isopened. The solution is then diverted by passing through conduits 63aand 63b into storage vessel 66 until such time as the centrifuge 58 canaccept more dirty detergent solution. At this time valves 31 and 33 areopened and valve 34 is closed. The fiow will then pass from storagevessel 66 through line 63C and open valve 33 to the main conduit 30feeding the centrifuge 58. With the reopening of valve 31 the fiow fromthe washer can flow to the centrifuge 58 simultaneously with the flowfrom storage vessel 66.

As a further alternate when the dirty detergent solution is divertedinto storage vessel 66, the solution may be first passed through conduit63d and over a screen 68 by clos- 'ing valve 34 and opening valve 67.Screen 68 will remove any relatively large size solids present in thedirty detergent solution before this solution is accumulated in storagevessel 66 and then released to the sludge removal centrifuge, thusrelieving the centrifuge of the task of removing large size solids.

The sludge removed from the dirty detergent solution is discharged fromthe rehabilitation circuit 55 through a conveyor 70.

in the settling basin 64 the detergent solution, with the sludgeremoved, is permitted to settle forming an o l-r ch upper layer of thelighter oil. A portion of this oll-TlC h upper layer of detergentsolution in the settling basin s continuously withdrawn through aconduit 72 to an oil separator 74, where the oil is separated from thedetergent solution and collected in an oil tank 75. The oil-f-reedetergent solution is then returned to the settling tank through a pump76, if required, and a conduit 77. Concentrated detergent solutionmakeup is added to the settling basin through a conduit 78 to restorethe desired concentration of the detergent. The restored detergentsolution in the settling basin 64 is heated, as by a hot water or steamcoil 80 submerged in the detergent solution. The heated and restoreddetergent solution is then withdrawn from the settling basin 64, throughan outlet 82 generally located well below the expected depth of theupper oil-rich layer, so as to avoid recirculating any oil in thedetergent solution. This heated restored detergent is then passed by apump 84, if required, through conduit 56 out of the rehabilitationcircuit to the spray pipes 24 on the washer 10.

As the sludge is removed from the dirty detergent solution by thecentrifuge 58 in the rehabilitation circuit, itis transferred byconveyor 70 to the end of conveyor 32 ad acent the feed end of dryer 36.At this point the sludge is then mixed with the cleaned metal waste andjointly fed into the feed chute 46 at the inlet of the dryer. As thesludge and metal waste is tumbled in the hot air stream of rotary dryer36, the moisture is removed and the light fine particles are carried bythe air stream as dust to the dust collector 42 where they are separatedfrom the air stream and drop to the dust collection hopper 43 from whichthe dust particles may easily be disposed of in their dried form. Theheavier solids, which from tests have greatly simplifies the disposalproblem of the sludge. Due to the loss of water and detergent solutionon the cleaned metal waste as discharged from the washer, and from therehabilitation circuit in the form of the wet sludge removed from thedirty detergent solution, the restored detergent solution in thesettling basin must be replenished and its concentration brought up toits desired strength before recirculating this restored detergentsolution to the spray pipes 24 on washer 10. In this improved step, themakeup water is added from a fresh water supply conduit 86 through spraypipes 87 at the upper end of the conveyor 32, which carries the cleanedmetal waste to the drying system 35, but just below the point at whichconveyor 70 feeds the wet sludge into conveyor 32, so as to not dilutethe sludge and possibly create a counterfiow with -the makeup water ofsome of the fines in the sludge back into the rehabilitation circuit.The makeup water rinses the cleaned metal waste of a substantial portionof any remaining detergent solution as the waste is being conveyed,usually on an incline so as to be elevated sufliciently to fiow bygravity into the dryer feed inlet chute 46. This rinse water with therecovered detergent solution then overflows an outlet weir 88 at thelower end of conveyor 32 and passes in conduit 90 to the setling basin64 where it helps to replenish the detergent in the restored detergentsolution. When the concentration of the detergent in the settling basin64 is still not up to the desired strength, the balance of the requiredmakeup is controllably added as concentrated detergent solution throughthe concentrated detergent makeup conduit 78 and valve 79 into thesettling basin 64 where the various solutions from conduits 60, 77, 78and 90 have a chance to mix before recirculated through conduit 56 tothe spray pipes 24 and washer 10. Thus, this further step of rinsing thecleaned metal waste with the makeup water provides a significantrecovery in the amount of the relatively expensive detergent solutionwhich can then be recirculated.

Although the best mode contemplated for carrying out the presentinvention has been shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention as defined by theattached claims.

What is claimed is:

1. A continuous non-batch process for cleaning oilladen metal waste torecover the metal and to reclaim the oil carried by the metal waste,comprising the steps of:

(a) washing the metal waste with detergent, and efi'ecting relativemovement between the waste and the detergent to create a counter-currenttherebetween;

(b) separating oil and detergent from the wash residue to leave a sludgecontaining moisure and dirt particles;

(c) mixing the sludge with the washed metal waste;

and

(d) drying the mixture of sludge and metal waste.

2. The process of claim 1 including the step of blowing from the metalthe dirt remaining after the moisture has been removed from the sludgein the drying process.

3. A continuous non-batch process for cleaning oilladen metal waste torecover the metal and to reclaim the oil carried by the metal waste,comprising the steps of:

(a) washing the metal waste with detergent solution, the metal wastemoving in a direction opposite to the detergent solution and beingagitated to give maximum exposure of the surfaces of the metal wasteparticles to washing by the detergent solution;

(b) reclaiming the detergent solution from the wash residue;

(c) rinsing the washed metal with water to remove any remainingdetergent solution therefrom;

(d) adding the rinse water to the reclaimed detergent solution forreuse;

(e) removing a sludge containing moisture and dirt particles from thewash residue; and

(f) combining the sludge with the washed metal after the rinsing step.

4. The process of claim 3 including the step of adding detergent to thereclaimed detergent solution to achieve the desired concentration.

5. The process of claim 4 including the step of heating the reclaimeddetergent solution with the added detergent.

6. The process of claim 5 including the step of recirculating the heatedreclaimed detergent solution with the added detergent to the washingstep.

7. A continuous non-bath process for cleaning oil-laden metal waste torecover the metal and to reclaim the oil carried by the metal waste,comprising the steps of:

(a) washing the metal waste in a wash bath with a heated detergentsolution, the metal waste moving in a direction opposite to thedetergent solution and being agitated to give maximum exposure of thesurfaces of the metal waste particles to washing by the heated detergentsolution;

(b) passing the dirty detergent solution removed from the wash baththrough a rehabilitation circuit to separate a sludge containingmoisture, fine dirt particles and fine metal particles and to remove oilfrom the dirty detergent solution;

(c) mixing the sludge with the washed metal waste;

(d) passing heated air through the mixed metal waste and sludge in adirection opposite to the flow of the metal waste and sludge to removemoisture therefrom; and

(e) recirculating the rehabilitated detergent solution to wash bathafter adding concentrated makeup detergent solution and after reheatingthe combined solu tions.

8. The process of claim 7 including the steps of removing in the heatedair passing through the mixed sludge and washed metal waste the finedirt particles from the sludge and separating the fine dirt particlesfrom the heated air in a dust collector.

9. A continuous non-batch process for cleaning oil-laden metal waste torecover the metal and to reclaim the oil carried by the metal waste,comprising the steps of:

(a) Washing the metal Waste in a wash bath with a heated detergentsolution, the metal waste moving in a direction opposite to thedetergent solution and being agitated to give maximum exposure of thesurfaces of the metal waste particles to washing by the heated detergentsolution;

(b) passing the dirty detergent solution removed from the wash baththrough a rehabilitation circuit to separate a sludge containingmoisture, fine dirt particles and fine metal particles and to remove theoil from the dirty detergent solution;

() adding makeup water to the washed metal waste removed from the washbath and rinsing the washed metal waste to remove any remainingdetergent solution therefrom;

(d) returning the rinse water with the detergent solution to therehabilitation circuit for recovery of the detergent solution and reusein the wash bath; and

(e) mixing the sludge with the washed metal after the rinsing step.

10. The process of claim 9 including the steps of adding concentrateddetergent solution to the combined rehabilitated detergent solution andthe returned rinse water to bring the concentration of detergent in thecombined rehabilitated detergent solution and returned rinse water tothe desired strength for washing oil-laden metal waste, reheating thecombined detergent solution and rinse water and recirculating the heatedcombined detergent solution and rinse water of desired detergentconcentration strength to the wash bath.

11. A continuous non-batch type process for cleaning oil-laden metalwaste to recover the metal and to reclaim the oil carried by the metalwaste, comprising the steps of:

(a) agitating and moving the metal waste through a flow of heateddetergent solution forming a wash bath, the movement of the metal wastebeing in a direction opposite to the flow of the detergent solution andthe agitation of the metal waste giving maximum exposure of the surfacesof the metal waste particles to cleaning by the detergent solution;

(b) removing the dirty detergent solution from the wash bath after itsexposure to the metal waste and passing the dirty detergent solutionthrough. a rehabilitation circuit, removing sludge and oil therefrom, torestore the detergent solutions cleaning capability,

(c) removing the cleaned metal waste from the wash bath and adding thesludge, removed from the dirty detergent solution in the rehabilitationcircuit, to the cleaned metal waste;

((1) removing a substantial quantity of the remaining moisure from thecleaned metal waste with the added sludge; and

(e) recirculating the restored detergent solution to the wash bath afterconcentrated makeup detergent solution was added and the combinedconcentrated makeup and restored detergent solution were heated in therehabilitation circuit.

12. A continuous non-batch type process for cleaning oil-laden metalwaste to recover the metal and to reclaim the oil carried by the metalwaste, comprising the steps of:

(a) agitating and moving the metal waste through a flow of heateddetergent solution forming a wash bath, the movement of the metal wastebeing in a direction opposite to the flow of the detergent solution andthe agitation of the metal waste giving maximum exposure of the surfacesof the metal waste particles to cleaning by the detergent solution;

(b) removing the dirty detergent solution from the wash bath after itsexposure to the metal waste and passing the dirty detergent solutionthrough a rehabilitation circuit, removing sludge and oil therefrom, torestore the detergent solutions cleaning capability;

(c) conveying the cleaned metal waste from said wash bath and addingmakeup water to the cleaned metal waste, said makeup water passingcounterflow to said metal waste and rinsing a substantial portion of anyremaining detergent solution from said metal waste;

(d) returning said makeup water with the additional rinsed-off detergentsolution to the restored detergent solution in the rehabilitationcircuit to thereby recover additional detergent solution and to reducethe amount of concentrated makeup detergent solution required;

(e) removing a substantial quantity of the remaining moisture from thecleaned metal waste; and

(f) recirculating the restored detergent solution to the wash bath afterconcentrated makeup detergent solution was added and the combinedconcentrated makeup detergent solution, the makeup rinse water, and therestored detergent solution were heated in the rehabilitation circuit.

13. A continuous non-batch type process for cleaning oil-laden metalwaste to recover the metal and reclaim the oil carried by said metalwaste, comprising the steps of:

(a) providing a flow of detergent solution in a first direction to forma wash bath for cleaning the metal waste by submersion in said detergentsolution and for removing the oil carried by said metal waste;

(b) propelling the metal waste through the flow of detergent solution ina direction generally opposite to the direction of how of said detergentsolution to provide counterfiow of metal waste and detergent solution,the propelling of the metal waste through the bath serving to agitatesaid metal waste and thereby to give maximum exposure of the surfaces ofthe metal waste particles to cleaning by said detergent solution;

(0) removing the cleaned metal waste from the wash bath;

(d) removing the detergent solution from the bath after its exposure tothe metal waste and passing the detergent solution, carrying sludge andoil therewith, through a rehabilitation circuit to restore the detergentsolutions cleaning capability;

(e) subjecting all of said detergent solution in said rehabilitationcircuit to centrifugal force to separate sludge, acquired by saiddetergent solution in cleaning said metal waste, and containing moistureand lightweight dirt particles from the detergent solution and oil;

(f) conveying and mixing said separated sludge with the cleaned metalwaste removed from the wash bath;

(g) removing a substantial quantity of the remaining moisture from saidmixed metal waste and sludge;

(h) accumulating the separated detergent solution and oil in a settlingbasin in the rehabilitation circuit after the separation of the sludge;

(i) withdrawing a portion of the accumulated oil-rich liquid fromadjacent the top of the settling basin, subjecting the withdrawn portionto centrifugal force to sepaarte the oil from the detergent solution torestore the detergent solution and returning the remainder of saidwithdrawn portion, from which the oil has been sepaarted, to thesettling basin;

(j) adding concentrated makeup detergent solution to the restoreddetergent solution in the rehabilitation circuit;

(k) heating said makeup and restored detergent solution in saidrehabilitation circuit; and

(l) recirculating the heated makeup and restored detergent solution fromthe rehabilitation circuit to the wash bath.

14. The process of claim 13 wherein the substantial quantity ofremaining moisture is removed from the mixed sludge and metal waste bypassing a stream of heated air through the mixed sludge and metal wastewhile moving through a rotary dryer.

15. The process of claim 14 wherein the sludge is added to and mixedwith the cleaned metal waste as the waste is being conveyed from thewash bath to the dryer.

16. The process of claim 15 further including the steps of entrapping inthe heated air stream the lightweight dirt particles remaining after themoisture has been removed from the sludge and separating the dirtparticles from the n heated air stream in a dust collector.

17. A continuous non-batch type process for cleaning oil-laden metalwaste to recover the metal and reclaim the oil carried by said metalwaste, comprising the steps of:

(a) providing a flow of detergent solution in a first direction to forma wash bath for cleaning the metal waste by submersion in said detergentsolution and for removing the oil carried by said metal waste;

(b) propelling the metal waste through the flow of detergent solution ina direction generally opposite to the direction of flow of saiddetergent solution to provide counterflow of metal waste and detergentsolution, the propelling of the metal waste through the bath serving toagitate said metal waste and thereby to give maximum exposure of thesurfaces of the metal waste to cleaning by said detergent solution;

() removing the detergent solution from the bath after its exposure tothe metal waste and passing the detergent solution, carrying sludgeacquired by the detergent solution in cleaning said metal waste and oiltherewith, through a rehabilitation circuit to restore the detergentsolutions cleaning capability;

(d) subjecting all of said detergent solution in said rehabilitationcircuit to centrifugal force to separate Sludge from the detergentsolution and oil;

(e) accumulating the separated detergent solution and oil in a settlingbasin;

(f) withdrawing a portion of the oil-rich liquid from adjacent the topof the settling basin and subjecting the withdrawn portion tocentrifugal force to sep arate the oil from the detergent solution torestore the solution, the remainder of said withdrawn portion, fromwhich the oil has been separated, being returned to the settling basin;

(g) removing and conveying the cleaned metal waste from said wash bath;

(h) adding makeup water to the cleaned metal waste being conveyed fromsaid wash bath, said makeup water passing counterflow to said metalwaste and rinsing a substantial portion of any remaining detergentsolution from said metal waste;

(i) passing said makeup water with the additional rinsed-01f detergentsolution to the settling basin in said rehabilitation circuit to therebyrecover additional detergent solution;

(j) separating a substantial quantity of the remaining moisture fromsaid cleaned and rinsed metal waste;

(k) adding concentrated makeup detergent solution to the restoredsolution in the rehabilitation circuit;

(1) heating said makeup and restored detergent solution in saidrehabilitation circuit; and

(m) recirculating the heated makeup and restored detergent solution fromsaid rehabilitation circuit to said wash bath.

18. The process of claim 17 further including the step of adding andmixing the sludge, separated from the detergent solution in therehabilitation circuit, with the cleaned metal waste being conveyed tothe means for separating a substantial quantity of the remainingmoisture in the metal waste.

19. The process of claim 18 wherein said sludge is added to the cleanedmetal waste as it is being conveyed but after the point at which themakeup water is added to the metal waste to avoid rinsing and furtherdilution of said sludge as it is being mixed and conveyed with the metalwaste to the means for separating the remaining moisture.

20. The process of claim 17 further including the step of accumulatingthe detergent solution, with the sludge and oil therein as removed fromthe wash bath, in a storage vessel prior to subjecting the detergentsolution to centrifugal force to separate the sludge, to enablecontinuous operation of the wash bath while the means for separating thesludge by centrifugal force is intermittently shut down for cleaning.

21. The process of claim 20 including the further steps of providing forthe overflow of any excess liquid in the settling basin and passing thisoverflow of excess liquid to the storage vessel.

22. The process of claim 20 including the further steps of screening thedetergent solution, with the sludge and oil therein as removed from thewash bath, to remove any larger size solids from the solution andpassing the undersize material from the screening step to andaccumulating this undersize material in the storage vessel.

References Cited UNITED STATES PATENTS 3,639,172 2/1972 Keogh l3425 R3,544,369 12/1970 Keogh 13425 R 3,610,260 10/1971 Kearney 134-19 X2,852,418 9/1958 MacDonald 1'34-2 2,925,821 2/1960 MacDonald 13410 X1,580,723 4/1926 Hapgood 13410 3,734,776 5/1973 Keogh 134-25 R 3,598,6498/1971 Juhasz 134--25 R X 3,454,428 7/1969 Hittel et al 13425 R3,163,929 1/1965 Goodstein 134-25 R 3,767,179 10/1973 Larson 1342 X S.LEON BASHORE, Primary Examiner R. H. TUSHIN, Assistant Examiner US. Cl.X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENTNO.:3,846,173

DATED November 5, 1974 |NVENTOR(5) 1 JOHN KENNETH II-IRIG It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

line 70, change "Hoper" to --Hopper.

Column 1,

Column 3, line 5, change "3,554,369" to 3,544,369-. Column 4, line 59,change "63C" to --63c--.- Column 6, line 1, insert being-- before"recirculated".

Column 8, line 72, change "sepaarte" to separate; line 75, change"sepaarte" to -separate.

Signed and Sealed this sixteenth D ay Of December 19 75 [SEAL] AIICSI.

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nj'Parenrsand Trademarks

1. A CONTINUOUS NON-BATCH PROCESS FOR CLEANING OILLADEN METAL WASTE TORECOVER THE METAL AND TO RECLAIM THE OIL CARRIED BY THE METAL WASTE,COMPRISING THE STEPS OF: (A) WASHING THE METAL WASTE WITH DETERGENT, ANDEFFECTING RELATIVE MOVEMENT BETWEEN THE WASTE AND THE DETERGENT TOCREATE A COUNTER-CURRENT THEREBETWEEN; (B) SEPARATING OIL AND DETERGENTFROM THE WASH RESIDUE TO LEAVE A SLUDGE CONTAINING MOISTURE AND DIRTPARTICLES;